Core retrieving apparatus

ABSTRACT

Apparatus for retrieving cores while drilling a borehole which enables an elongated cylindrical solid core sample to be obtained from a formation. A coring bit together with a core barrel which remains stationary with respect to the core being cut enables the core to be broken into predetermined lengths and circulated uphole to where the core is captured within a core retriever made in accordance with the present invention, and which enables the intact core to be removed from the drill string.

United States Patent Elenburg [54] CORE RETRIEVING APPARATUS [72] Inventor: Wayland D. Elenburg, PO. Box 1588,

Monahans, Tex. 79756 [22] Filed: Dec. 16, 1970 [211 Appl. No.: 98,634

Related US. Application Data [60] Division of Ser. No. 831,361, June 9, 1969, Pat. No. 3,596,723, which is a continuation-in-part of Ser. No. 714,551, March 20, 1968, Pat. No. 3,473,617.

[52] U.S. CI ..l75/2l5, 175/254 51 1 Int. Cl "1521b 9/20 [58] Field 01 Search ..175/60, 215, 249, 254, 245

[56] References Cited UNITED STATES PATENTS 1,224,509 5/1917 Smith ..l75/254 1,574,731 2/1926 Foster ..175/249 X [451 July 18,1972

2,012,294 8/1935 Wright et a1. ..175/254 2,364,088 12/1944 Miller et a1 175/245 X 2,540,385 2/1951 Biggs ..175/60 3,155,179 11/1964 Hunt et al ....175/60 X 3,323,604 6/1967 Henderson ..175/215 X Primary Examiner-David H. Brown Attomey-Marcus L. Bates [57] ABSTRACT Apparatus for retrieving cores while drilling a borehole which enables an elongated cylindrical solid core sample to be obtained from a formation. A coring bit together with a core barrel which remains stationary with respect to the core being cut enables the core to be broken into predetermined lengths and circulated up-hole to where the core is captured within a core retriever made in accordance with the present invention, and which enables the intact core to be removed from the drill string.

11 Claims, 8 lhawing flgiu'es Patented July 18, 1972 3 Sheets-Sheet l INVENTORi WAYLAND D. ELENBURG BY MARCUS L. BATES Patented July 18, 1972 3 Sheets-Sheet 5 M J w R RKKRA IllllnllllII-llll'lllllllllll-lllllilllllllllllllllll kill] m\\\\\\\\\\\\ NWQM INVENTOR. WAYLAND D.v ELENBURG BY MARCUS L. BATES CORE RE'I'RIEVING APPARATUS This is a division of Pat. application, Ser. No. 831,361 filed June 9, 1969; now US. Pat. No. 3,596,723 issued Aug. 3, 1971, which was a continuation-in-part of US. Pat. No. 3,473,617.

BACKGROUND OF THE INVENTION Reference is made to my US. Pat. No. 3,439,757, issued Apr. 22, 1969, and to US. Pat. No. 3,473,617 for background of the present invention. In carrying out drilling operations according to my previous patent and patent applications, it has been found that passage of a solid core sample through the conventional gooseneck of a coring rig causes substantial damage to the core and it is therefore desirable to be able to obtain a core intact from the formation so as to receive a more representative sample of the material which forms the borehole. Moreover, it is desirable to be able to obtain undamaged core samples which are of a much longer length than is presently possible using conventional coring and retrieving a paratus. It is also desirable to be able to achieve cores of a predetermined length by manipulation of the drill string which in turn breaks the cores into an arbitrary length.

SUIVIMARY OF THE INVENTION The present invention comprehends both method and apparatus for carrying out an improved boring, coring, and retrieving operation while forming a borehole, and specifically relates to method and apparatus for obtaining undamaged lengths of cores from the bottom of a borehole. Concentrically arranged pipe forming a drill string having a central and annular passageway formed therein for circulating fluid to the bit and for providing a return flow path for obtaining the core is suitably connected to a core cutting bit by a combination sub and core barrel. A core retriever assembly is interposed in series relationship within the inner tubing at a location near the kelly. Drilling fluid is forced down through the annulus of the drill ipe or drill string and into close proximity of the cutting teeth of the bit, causing fluid to be forced either back up through the hole annulus or up through the inner tubing, as may be desired. A core barrel attached in journaled relationship to the drill bit is maintained stationary with respect to the core being cut. A core catcher cooperates with the core and core barrel in a manner to maintain the core barrel in a nonrotating condition with respect to the core being cut. When it is desired to break the partially formed core from the formation, the drill string is elevated, whereupon the core is broken away from the formation and circulated up-hole by drilling fluid. The core travels up-hole within the inner tubing and is captured within a core retriever. If desired, an identical core retriever can be substituted for the one which contains the cut core in order to enable the drilling operation to be immediately resumed with little interruption thereof.

It is therefore a primary object of the present invention to provide a method of obtaining core samples from a borehole by forming elongated cores and circulating the cores back to the surface of the earth by an improved flow pattern.

Another object of the present invention is the provision of apparatus for retrieving intact elongated cores during a core drilling operation.

A further object of the present invention is the provision of a stationary core barrel which is maintained in non-rotating condition with respect to the core and which includes an improved core catcher, core breaker, and means for maintaining the core barrel stationary with respect to the core being cut.

A still further object of the present invention is the provi sion of a core retriever assembly for use in conjunction with a non-rotating core barrel.

The above objects are attained in accordance with the present invention by the provision of concentrically arranged drill pipe which are connected to a bit, to a non-rotating core barrel, and to a core retrieving assembly, all of which cooperate together to provide an improved means by which cores may be obtained from the interior of the earth.

These and other objects of the present invention will become apparent to those skilled in the art as the description of the invention proceeds.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a diagrammatical cross-sectional representation of the earths structure with the present well boring apparatus being operatively positioned therein in order to broadly explain the operation of the present invention;

FIG. 2 is an enlarged cross-sectional view of part of the apparatus seen in FIG. 1;

FIG. 3 is an enlarged fragmentary cross-sectional view taken along line 33 of FIG. 2;

FIG. 4 is an enlarged fragmentary cross-sectional view taken along line 4-4 of FIG. 2;

FIG. 5 is an enlarged cross-sectional view of part of the apparatus disclosed in FIG. 1, with parts thereof being broken away from one another and connected by dot-dashed lines in order to better illustrate the invention; and

FIGS. 6, 7, and 8, respectively, are cross-sectional views taken along lines 6, 7, and 8 respectively, of FIG. 5.

DETAILED DESCRIPTION OF THE INVENTION FIG. 1 schematically sets forth a portion of a well drilling apparatus 10 which is in the act of boring a hole into the earth's structure. Part of the apparatus is located above the surface 1 l of the earth, while the remainder of the apparatus is located downhole in the usual manner. Circulation of drilling fluid is accomplished by means of swivel 12, the details of which are known in the art, with fluid flow occurring to and from the apparatus as indicated by the arrows at numeral 13. A kelly I4 is rotated by conventional means, not shown. A core retriever 16, made in accordance with the present invention and having upper and lower inner tubing connection means l8, 19, respectively, is concentrically received within drill string 20 which is made up of a multiplicity of drill pipe joints 22.

Connected to uppermost inner tubing joint 24 is a multiplicity of inner tubings M which extend downhole at 24' to a core barrel. The inside peripheral wall surface of the drill pipe or drill collar, which ever may be used, is seen at 25. A drill bit 26 has a core receiving aperture 28 which is of a size to enable core barrel 30 to receive core 32 therein as the core is being formed. Spaced apart guide means 33 maintains the core barrel aligned within the lower depending end of the string, all in a manner as described in my before identified US. Pat. No. 3,473,617.

Looking now to FIG. 2, an enlarged cross-sectional view of the before mentioned outer and inner barrel and bit are shown in detail. It should be understood that the device of FIG. 2 is connected to the drill suing and related apparatus of FIG. 1. The annulus formed between the inner and outer tubing provides an annular passageway 44 with the core barrel being attached to the sub by means of a bearing such as seen at 46. A collar 48 threadedly engages the core barrel in a manner to capture the bearing therebetween as illustrated at 50. The central portion 52 of the barrel extends downwardly to where it threadedly engages member 54, the depending end of which forms a shoulder at 55.

Threadedly attached to the lower terminal end of the core breaker member is a cylindrical downwardly converging core catcher housing 60 having a key 62 thereon, and which includes vertically spaced apart splines thereon (not shown) which cooperate with similar spaced apart splines provided on the outside peripheral wall surface of the inverted frusto-conical core catcher and breaker 64, the details of which are best seen in FIG. 3. The lower terminal end portion of the core barrel temiinates at 61. The inside face of the drill bit is provided with grooves 67, having a bottom-most portion 68, to thereby leave a passageway between the lower terminal end of the inner barrel and the inside of the bit.

core barrel and the inside peripheral wall surfaceof the outer barrel. The passageway continues as seen at 73 to where it branches into a multiplicity of radially spaced apart passageways 74 which are drilled through the before mentioned sub 42 so as to communicate at 75 with the annular passageway formed by the drill string.

FIG. 5, in conjunction with FIGS. 6, 7, and 8, sets forth the details of the before mentioned core retriever generally illustrated at 16 in FIG. 1. Sub 76 is series connected at 18', I9 and forms a part of the drill string. The inside peripheral wall of the sub downwardly diverges at 77 to form chamber 77. The upper end of the sub is counterbored to form a shoulder 78 located between inlet 18' and the before mentioned chamber.

Outer peripheral wall surface 79 of the core retriever cooperates with the inside peripheral wall surface of the drill pipe sub to form annulus 80. Upper connection 18 is provided with cross 82 which forms a core abutment means therein. Circumferentially extending seal means 83 enables the upper marginal end portion of the retriever to be telescopingly received in. sealed relationship within the upper connection. Enlargement 85 includes upper and lower opposed shoulders, the lower one of which is abuttingly received against the before mentioned shoulder 78. Optionally provided between the enlargement and the chamber is a downwardly and outwardly diverging portion 86 which terminates in the illustrated circumferentially extending edge portion for facilitating removal of the retriever. Intermediate the depending ends of the retriever there is provided a second core catcher housing 87 having a downwardly depending threaded skirt at 87 which threadedly engages lower portion 89 of the retriever, with the housing enclosing the second core catcher assembly generally illustrated by the arrow at numeral 88.

Radially spaced apart guide means 89' are slidably received by the inside peripheral wall 90 of the sub so as to maintain the 1 lower end portion of the retriever centrally aligned with respect to the drill pipe sub.

The core catcher assembly 88 includes the illustrated spaced apart cages 91 which are received within recesses provided within the housing. A plurality of individual fingers 92 are provided and are pivotally attached to the cages by pin 93. The fingers may be rotated from the core catching position at 92 to the core passing or retracted dot-dashed line position seen at 92'. A spring biasing means (not shown) can be included for urging the fingers into the closed position, if desired.

Annulus 93 is formed between the outer wall of the upper connection and the inside wall surface of the drill pipe. Radially spaced apart ports 94 are in fluid communication with annulus 93' and 95. ,The second core catcher housing is spaced apart from chamber 77 to form annular flow path 96 therethrough. Between guide means 89' there is provided several flow passageways 97, while the lower female connection is spaced apartfrom the pin or male connection of the drill pipe so as to provide an annular passageway 98 which is aligned with theannulus formed between the inner tubing and the drill pipe.

OPERATION In operation the swivel supports the drill string in a conventional manner with drilling fluid flowing to and from the bit by means of passageways at 13. The kelly imparts rotational motion into the bit in the usual manner. The fluid flow path can be traced from the swivel, through the annulus between the uppermost joint of the inner tubing and the kelly, through annulus 93', ports 94, annulus 95, annular chamber 96, passageways 97, annulus 98, down the drill string annulus and around the lower barrel at 44-where the fluid is available for cleaning, washing, and cooling the drill bit. The flow can now return to the surface by means of the hole annulus or alternatively, it can flow up through the inner tubing, depending upon the controlled hydrostatic condition of the particular boring operation as previously explained in my copending patent application.

As core 32 is formed or received within the core barrel the lowermost end of the core remains attached to the formation with the side walls of the core being telescopingly received in close fitting engagement by the lower core catcher so as to maintain the core barrel in a non-rotating condition; that is. the barrel is held stationary with respect to the formation. When a core of a desired length has been attained by the cutting action of the bit, for example, a three foot core sample, the drill string is lifted by means of the swivel. This action causes the lower core catcher to squeezingly engage the core with an increasing force due to the action of the core catcher with respect to its housing which forces the core catcher to assume a smaller diameter. Stated differently, the core catcher is forced downward against the sloped wall of its housing, causing an increased force to be exerted against the core while at the same time the upward movement of the drill pipe exerts an upward force upon the core sample, thereby breaking the lower end of the core away from the formation. After the core sample has been pulled apart from the formation it will be realized that the core is now held within the core catcher and barrel. The drill bit is again set down and several additional inches of fomiation penetration is made in order to commence forming a new core, the upper extremity of which pushes the previously cut core sample out of the core catcher and into the core barrel.

The freed core sample is now a free body analogous to a piston which is reciprocatingly received within a cylinder. As the drilling operation continues, the pressure differential of drilling fluid across the freed core sample enables circulation of the core up-hole.

Circulation of drilling fluid forces the core uphole through the inner tubing where it must eventually enter the core retriever and contact the abutment means or cross 82, thereby causing the core to be captured within the core retriever. As the core sample enters the lower portion of the core retriever, fingers 92 are pivoted fromthe illustrated position seen at 92 into the dot-dashed position seen at 92'. As the lower end portion of the core sample pawes clear of the upper core catcher, the fingers return to the illustrated position seen at 92. Where deemed desirable, each of the fingers may be spring loaded or biased into the horizontal or core catching position 92.

As the core abuts the cros 82 a pronounced increase in the drilling fluid pressure indicates that the core has arrived within the core retriever or receiver, whereupon the kelly is picked up by the swivel, set down on a set of slips located within a conventional bowl, and the sub 76 is then disengaged from the kelly at 18', thereby enabling the inner tubing to be broken at upper connection 18 so as to enable the core retriever to be removed from the sub. The upper .connection is removed and the core sample is emptied into a tray by merely inverting the retriever, after which it is assembled and replaced within the sub, the upper connection made back up, the kelly screwed back onto the upper connection 18', whereupon the slips are removed, the bit set back on bottom, and drilling recommenced in order to cut and obtain the next core section.

Where deemed desirable, an extra sub having a core retriever therein can be substituted for the sub and retriever which contains the core sample, thereby gaining-a few seconds time and enabling the core sample to be removed from the core retriever in a more leisure manner.

penetrated. The core catcher can be ribbed or splined as seen in FIG. 2, or alternatively, it can be provided with an inside peripheral wall surface comprised of highly abrasive particles such as realized by brazing or otherwise surfacing the catcher with tungsten carbide particles or the like.

The location of the sub which contains the retriever is not considered critical so long as it is interposed within the drill string at a position which pennits access thereto during the drilling operation. Furthermore, those skilled in the art will realize that several different circulation patterns can be carried out while using the present invention, as for example, the return fluid can flow up the hole annulus, up the inner tubing, or a combination of both.

The maximum core length attainable with the present invention is determined by the length of the core retriever and to some extent by the length of the core barrel. However, it is preferred to cut cores slightly more than 3 feet in length because a core of this length provides adequate pressure drop thereacross in order to develop sufficient force to cause the core to travel up-hole to where it is captured within the core retriever.

I claim:

1. A well drilling apparatus having a rotatable drill bit for cutting cores from formations, with the bit being connected to concentrically arranged drilling pipe and tubing which forms a central and an annular passageway for the countercurrent circulation of drilling fluid therethrough;

a central aperture longitudinally disposed in the bit for receiving cores therethrough with the central aperture being flow connected to the inner tubing of the drilling string for enabling the cut cores to be forced upwardly therethrough and towards the surface of the earth; in combination:

a core retriever having upper and lower connecting means by which it can be interposed in series relationship within the inner tubing at a location spaced apart from the upper terminal end of the drill string;

an abutment means, an upper core catching means, said abutment and core catcher being spaced apart from one another and located within said retriever with said upper core catcher underlying said abutment means; said abutment means adapted to permit fluid flow therethrough while precluding passage of a core therethrough; said upper core catcher adapted to permit fluid flow therethrough and to permit up-hole passage of a core therethrough while preventing downhole passage of a core therethrough;

said core retriever being spaced apart from the drill pipe to form an annular passageway which is in communication with the drill string annular passageway; whereby:

fluid flow can occur down the drill string annulus while cores can be circulated up-hole through the inner tubing and into the core retriever where the core is captured between the abutment and upper core catcher.

2. The combination of claim 1 wherein said upper core catcher includes a housing, spaced apart fingers located in a common plane and within said housing, journal means for pivoting each finger from a core passing to a core catching position.

3. The combination of claim 1 wherein said core retriever includes means by which it is supported by the drill pipe;

means provided on each marginal end portion of said retriever for enabling the retriever to sealingly engage the depending j' end portions of the remainder of the inner tubing; whereby: 1 '65 said retriever, when the drill string is broken down, can be removed from the drill pipe. 4. The combination of claim 1 wherein said core retriever includes means forming an outwardly directed enlargement about a mid-portion thereof;

a sub adapted to be series connected into the drill pipe, a

shoulder formed internally of said sub, said retriever adapted to be telescopingly received within said sub with said enlar e men t engatginlg said shoulder. 5. The corn matron o carm 1 wherein said abutment means is comprised of a plurality of spaced apart rods aligned in a common plane, said abutment means being affixed to said upper connection means; whereby:

removal of the connection means enables the core to be removed from the core retriever.

6. The combination of claim 5 wherein said upper core catcher includes a housing, spaced apart fingers located in a common plane and within said housing, journal means for pivoting each finger from a core passing to a core catching position.

7. in a well drilling apparatus having a drill bit for cutting cores from formations, wherein the bit is connected to concentrically arranged inner tubing string and outer drill pipe string which cooperate together to fomi concentrically arranged longitudinally extending central and annular passageways for the countercurrent flow of drilling fluid therethrough, the improvement comprising:

a sub including means thereon by which said sub can be series connected within the drill pipe string;

an elongated core retriever having upper and lower connection means thereon for enabling said retriever to be removably connected in series respective of the tubing string;

said core retriever being telescopingly received within said sub, support means formed on said sub and said retriever for positioning said retriever within said sub so that the retriever can be removably placed within said sub;

flow passageway means for enabling fluid flow through the sub along the annular passageway; central flow passageway means formed through said retriever for enabling fluid flow along the central passageway; said central flow passageway means including a core abutment means, a core housing, and a core catcher assembly; said core catcher assembly underlying said core housing, said core abutment means overlying said core housing; whereby:

said sub can be connected into the drill pipe string and said retriever can be telescopingly placed within said sub and connected into the tubing suing whereupon a core sample can then be circulated from the bit, up the tubing string, past the core catcher, and into the core housing where the core abutment means retains the core sample within the core housing of the core retriever.

8. The combination of claim 7 and further including a connection means connected to an upper portion of said housing; said core abutment means being comprised of a plurality of spaced apart rods aligned in a common plane and afiixed to said upper connection means; whereby:

removal .of the connection means enables the core to be removed from the core retriever. V

9. The combination of claim 7 wherein said core catcher includes a core catcher housing, spaced apart fingers located in a common plane and within said housing, and journal means for pivoting each finger from a core passing to a core catching position.

10. The combination of claim 7 wherein said upper core catcher includes a core catcher housing, spaced apart fingers located in a common plane and within said housing, journal means radiallyspaced apart from one another for pivoting each finger from a core passing to a core catching position.

11. The combination of claim 7 wherein said support means includes means forming an outwardly directed enlargement about a mid-portion of said retriever; a shoulder formed internally of said sub, said enlargement of said retriever adapted to supportingly engage said shoulder. 

1. A well drilling apparatus having a rotatable drill bit for cutting cores from formations, with the bit being connected to concentrically arranged drilling pipe and tubing which forms a central and an annular passageway for the countercurrent circulation of drilling fluid therethrough; a central aperture longitudinally disposed in the bit for receiving cores therethrough with the central aperture being flow connected to the inner tubing of the drilling string for enabling the cut cores to be forced upwardly therethrough and towards the surface of the earth; in combination: a core retriever having upper and lower connecting means by which it can be interposed in series relationship within the inner tubing at a location spaced apart from the upper terminal end of the drill string; an abutment means, an upper core catching means, said abutment and core catcher being spaced apart from one another and located within said retriever with said upper core catcher underlying said abutment means; said abutment means adapted to permit fluid flow therethrough while precluding passage of a core therethrough; said upper core catcher adapted to permit fluid flow therethrough and to permit up-hole passagE of a core therethrough while preventing downhole passage of a core therethrough; said core retriever being spaced apart from the drill pipe to form an annular passageway which is in communication with the drill string annular passageway; whereby: fluid flow can occur down the drill string annulus while cores can be circulated up-hole through the inner tubing and into the core retriever where the core is captured between the abutment and upper core catcher.
 2. The combination of claim 1 wherein said upper core catcher includes a housing, spaced apart fingers located in a common plane and within said housing, journal means for pivoting each finger from a core passing to a core catching position.
 3. The combination of claim 1 wherein said core retriever includes means by which it is supported by the drill pipe; means provided on each marginal end portion of said retriever for enabling the retriever to sealingly engage the depending end portions of the remainder of the inner tubing; whereby: said retriever, when the drill string is broken down, can be removed from the drill pipe.
 4. The combination of claim 1 wherein said core retriever includes means forming an outwardly directed enlargement about a mid-portion thereof; a sub adapted to be series connected into the drill pipe, a shoulder formed internally of said sub, said retriever adapted to be telescopingly received within said sub with said enlargement engaging said shoulder.
 5. The combination of claim 1 wherein said abutment means is comprised of a plurality of spaced apart rods aligned in a common plane, said abutment means being affixed to said upper connection means; whereby: removal of the connection means enables the core to be removed from the core retriever.
 6. The combination of claim 5 wherein said upper core catcher includes a housing, spaced apart fingers located in a common plane and within said housing, journal means for pivoting each finger from a core passing to a core catching position.
 7. In a well drilling apparatus having a drill bit for cutting cores from formations, wherein the bit is connected to concentrically arranged inner tubing string and outer drill pipe string which cooperate together to form concentrically arranged longitudinally extending central and annular passageways for the countercurrent flow of drilling fluid therethrough, the improvement comprising: a sub including means thereon by which said sub can be series connected within the drill pipe string; an elongated core retriever having upper and lower connection means thereon for enabling said retriever to be removably connected in series respective of the tubing string; said core retriever being telescopingly received within said sub, support means formed on said sub and said retriever for positioning said retriever within said sub so that the retriever can be removably placed within said sub; flow passageway means for enabling fluid flow through the sub along the annular passageway; a central flow passageway means formed through said retriever for enabling fluid flow along the central passageway; said central flow passageway means including a core abutment means, a core housing, and a core catcher assembly; said core catcher assembly underlying said core housing, said core abutment means overlying said core housing; whereby: said sub can be connected into the drill pipe string and said retriever can be telescopingly placed within said sub and connected into the tubing string whereupon a core sample can then be circulated from the bit, up the tubing string, past the core catcher, and into the core housing where the core abutment means retains the core sample within the core housing of the core retriever.
 8. The combination of claim 7 and further including a connection means connected to an upper portion of said housing; said core abutment means being comprised of a plurality of spaced apart rods aligned in a common plane and affixed to said upper connection means; Whereby: removal of the connection means enables the core to be removed from the core retriever.
 9. The combination of claim 7 wherein said core catcher includes a core catcher housing, spaced apart fingers located in a common plane and within said housing, and journal means for pivoting each finger from a core passing to a core catching position.
 10. The combination of claim 7 wherein said upper core catcher includes a core catcher housing, spaced apart fingers located in a common plane and within said housing, journal means radially spaced apart from one another for pivoting each finger from a core passing to a core catching position.
 11. The combination of claim 7 wherein said support means includes means forming an outwardly directed enlargement about a mid-portion of said retriever; a shoulder formed internally of said sub, said enlargement of said retriever adapted to supportingly engage said shoulder. 